n = int(input())
c = input()
nr = c.count('R')
nr2 = c[:nr].count('R')
print(nr - nr2) n = int(input()) n int(input()) int input() input c = input() c input() input nr = c.count('R') nr c.count('R') c.count c count 'R' nr2 = c[:nr].count('R') nr2 c[:nr].count('R') [:nr].count [:nr] c :nr nr count 'R' print(nr - nr2) print nr - nr2 nr nr2 nr = c.count('R') c.count('R') nr nr2 = c[:nr].count('R') c[:nr].count('R') nr2 c = input() input() c n = int(input()) int(input()) n
n = int(input())
c = input()
nr = c.count('R')
nr2 = c[:nr].count('R')
print(nr - nr2)